Cutter and method of forming the same



Oct. 21, 1952 GODDARD 2,614,441

CUTTER AND METHOD OF FORM ING THE SAME Filed April 4, 1947 E LET-J- I NVEN TOR. [MMO/VS 4. 5000/: RD

ATTORNEY Patented Oct. 21, 1952 signor l I This invention relatesgenerally to cutters and refers mor particularly to metal disc typeoutters having hub portions. Y I

Although it will be apparent as this descriptionproceeds thattheinvention is notlimited to any specific type of cutter, nevertheless, itfinds particular utility whenemployed in the manufacture of -circulardisc type cutters, such for example, as circular saws-having hub portions at the center and having ra'dially outwardly extendingrerelatiyelythin, web portions.

Circular cutters of the above general type have been diflicult toeconomically manufacture to the close. tolerances required for many usesof such cutters. Much of thedifi iculty heretofore encountered inproducing circular cutters is'Tdueto the non-uniform rate .o'f coolingof the cutters subsequent to'the heat' treating and/or side grindingoperations; This uneven rate of cooling is caused by the differences inmass of the hub and web portions; of the cutter.' The mass of the hubportion ordinarily exceedsthe mass of the web portion, andas aconsequence, cools at a, rate which is slow comparison to the rate ofcooling of thewvveb portionlThis differential. sets up strains in thecutterwhich are'frequently sufli'ciently severe to cause distorltion'iofthe cutter beyond repair. l T j Inorder to overcome the abovedifilculties, complicated and expensive heat treating techniques havebeen proposed- One heat treating Process advocated is to provide somemeans for accelerating the rate of cooling-.of thev hub to suchan extentthat this rate approximates the rate of cooling of the relativelythinweb. Another process is to attemptitoqhold the cutter against warping ordistorting by maintainingthe cutter clamped between heavy plates duringthe heating and cooling cycles of the heat treating operation. Stillanother process is to leave sufficient stock on the cutter so that anybuckle or distortion created during heat treating may be subsequentlyremoved by grinding before the thickness of the cutter becomesundersize.

Even where unusual care is taken in the performance of the above heattreating processes, the results obtained are unsatisfactory. Moreover,such special heat treating processes are not conducive to producingcutters on a high production basis, and at best add materially to thecost of finished cutters.

With the above in view, it is an object of this invention to overcomethe above diificulties experienced in producing heat treated circularEmmons -'A'. Goddard, Birmingham, 'Mich -"as to"- Goddard & GoddardCompany, De-

etroit, Mich., a corporation of Michigan i Application April4, 1947,Serial No 739,268 1 -3Claims. (01.7 5101) j 4' A more detailed, objectof this invention is to provide a. circular cutter .offthe general typestated, wherein the mass of the hub portion approxir'nates the massofthe radially extending web portion so that, practically speaking, therate oifcooling of "the'hub and rim portions are these-me or nearly so.Thus the cutter-maybe heat treated by, the simplestproc'es'ses withoutbuckling warping or otherwise "distorting the cutter..Moreover,'less'heat is generatedin the "ubs'equent side grindingoperation, and the tendency of the cutter to distort during grinding isreduced, to a minimum. It follows,'therefore, that clos'e tolerances maybeheld on dimensions of .1 thickness, flatness and concavity, Which. areprerequisites, ofsatisfactory'cuttersI t he foregoing as well. as otherobjects will be made more apparent as this description proceeds,especially when consideredin connection with the accompanying drawing,.whereinp Figure 1v is asid elevational .view of ac rcular disc typecutter constructed in accordance with this i invention;

1 QEigure 2 is a sectionalview taken ori-the line 25-2 of Figural;.Figure 3 is a side'elevationalview ofamodifiedli m-r utt r; a 1

'ew taken on the line ,Figure 4' is a sectional 4 4 ofFigurefi. 7 I 1 5For the purpose of illustrating this invention, acircular disc ,type sawis selected, although it will be understood as this description proceedsthat the invention may. be successfully employed in the production ofvarious othertYDfiS Ofcutters. Referring first to the embodiment of theinvention shown inFigures 1 and 20f the drawing, it will be notedthat'the reference numeral I0 designates 'a cutter in the form of acircular disc type saw formed of metal, such for example, as high speedsteel or any other type of steel possessing the requiredcharacteristics.

In detail the saw It! comprises a hub H and a web I2 extending radiallyoutwardly from the hub. The hub is formed with a central opening l3therethrough having a key receiving recess 4 and the periphery of theweb I2 is formed with a circumferential series of cutting teeth I 5. Inaccordance with conventional practice, the cutter is heat treated, andany orthodox process may be resorted to for this purpose. In general thecutter is heated to a temperature recommended for the particular metalemployed to obtain the desired temper and is then cooled in any suitablemanner.

The web I2 is relatively thin in comparison to the thickness of the hubII and sufficient metal 3 is removed from the hub to reduce the mass ofthe hub to a value approximating the mass of the web. In other words thebulk or quantity of material forming the hub H is substantially the sameas the bulk or quantity of material forming the web l2, although thethickness of the hub H is greater than the thickness of the web. In thepresent instance a pair of annular recesses or grooves I6 is formed inone face of the hub in concentric relation to the axis of the cutter anda second pair of annular grooves H is formed in the opposite face of thehub axially opposite the grooves I6. Also, if desired,

between opposite faces of the cutter in the surface of thecuttersurrounding the central opening 13. The amount of metal removed from thehub II bythe above mentioned grooves, or in other words, the size and/ornumber of grooves is predetermined to provide the hub with a massapproximating the mass of the web 12. Thus during the cooling phase ofthe heat treat mg. process, the hub I I cools at substantially the samerate as the Web I2, and the tendency for the cutter to buckle, distortor otherwise deform is, reduced to a minimum. It w1ll also be notedthatthe side walls'of the grooves provide heat 1 radiating surfaces whichfacilitate coolingof'the hub II and assist in preventing distortion ofthe cutterduring finish grinding the latter. a

' The embodiment of the invention shown in Figures 3 and 4ofthe drawingfeatures a disc type cutter ZUidentical to the cutter I0 except that therecesses'are in the form of a multiplicity of openings 2! drilled in thehub. The openings are spaced 'equal distances from each other around theaxis of the hub and serve to reduce the mass of the hub sufiiciently toenable the hub to cool atpracticallythe same rate as the web during thecooling phase of the heat treating operation.

It follows from the above that both embodiments of the invention providea disc type cutter having a hub and a webcharacterized in that the massof the hub approximates the mass of the web, so that the cutter coolspractically uniform- 13 during the cooling phase of the heat treatingoperation. Thus deformation of the cutter by strains set up in thecutter during the cooling phase is reduced to a minimum, and theproduction of a cutter to close tolerances'is rendered possible withoutresorting to special heat treating processes.

What I claim as my invention is:

1.111 a method of producing a heat treated metalcutter having contiguoushub and web portions, the web portion extending radially outwardly fromthe hub portion and being relatively thin as compared to the thicknessof the hub portion, the steps of reducing the mass and increasing thesurface area of the hub portion to an extent such that both saidportions cool at the same rate from an elevated temperature, the mass ofthe hub portion being reduced and the surface area thereof beingincreased without changing the overall thickness of the hub portion, andthereafter subjecting the cutter to a heat treating process including aheating and cooling phase.

2. The method defined in claim 1, in which the mass of the hub isreduced and the surface area thereof is increased by forming openings insaid hub portion at points spaced equal distances from each other aroundthe axis of the hub portion.

3. The method defined in claim 1, in which the mass of the hub isreduced and the surface area thereof is increased by forming, concentricannular grooves in at least. one radial face of the hub portion.

. EMMONS A. GODDARD.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS. Date Number I Name 63,487 Disston Apr. 2, 1867214,389 Hill Apr. 18, 1879 220,432 Sawyer et a1 Oct. 7, 1879 320,681 IPerkins June 23, 1885 468,742 Erickson Feb. 9, 1892 903,933 WilliamsNov. 17, 1908 910,137 Lehmann Jan. 19, 1909 927,164 Pufier July 6, 19091,351,499 Takano Aug. 31, 1920 1,837,344 Stauder Dec. 22, 1931 1,861,218Huther' May 31, 1932 2,064,407 Bird Dec. 15, 1936 2,169,632 DrummondAug. 15, 1939 2,214,827 Boeet al Sept. 17, 1940 2,297,611 Drummond Sept.29, 1942 2,338,990 Wenzel Jan. 11, 1944 FOREIGN PATENTS Number CountryDate 23,864 Great Britain Mar. 9, 1911 35,906 Sweden Dec. 10, 191368,001 Germany June 25, 1892 277,203 Germany July 28, 1914 358,429France Dec. 18, 19 5 598,793 Germany June 18, 1934

